This invention relates generally to a breathing method and apparatus for supplying air to a user at one altitude so as to simulate conditions at a higher altitude.
Persons who ordinarily function at a near-sea-level altitude frequently experience headache, shortness of breath, nausea, sleeplessness, and reduced endurance during the initial days at higher altitude, e.g. above 7,500 feet. These factors are, in large part, attributable to the diminishing amount of oxygen available as altitude increases. A typical situation involves a sea-level resident who occassionally takes a skiing weekend above 7,500 feet. As altitude increases, oxygen availability diminishes, thus requiring the person to breathe deeper in an effort to supply sufficient oxygen to his bloodstream. The partial pressure of oxygen (PO.sub.2) at 7,500 feet is only 75% (of the PO.sub.2 at sea level) and at 10,000 feet is only 65%. At 19,000 feet, the PO.sub.2 is only 50%, thus meaning that a unit volume of air at 19,000 feet contains only half as much oxygen as that same unit volume at sea level. Typically, after a few days at the higher altitude, the person will become acclimated and the aforementioned problems subside. Interestingly, evidence suggests that persons who experience high altitudes on a frequent and regular basis appear to maintain a certain degree of acclimation to the altitude and are considerably better able to avoid the aforementioned problems than infrequent visitors.
Applicant's parent and grandparent applications disclose a breathing method and apparatus for enabling a user, while at low altitudes, e.g. sea level, to experience higher altitude conditions.
Briefly, the apparatus disclosed in Applicant's prior applications, include inspiratory and expiratory tubes having first ends coupled to a breathing means which may include a mouth and/or nose mask. The remote end of the expiratory tube is coupled through a proportioning means to the environment and to a reservoir or air storage chamber. The remote end of the inspiratory tube is also coupled to the proportioning means so as to pull ambient air from the environment, as well as oxygen reduced air from the reservoir. By varying the proportioning means, the ratio of ambient air to expired air, and thus the oxygen concentration of the inspired air, is varied so as to enable the user to select a particular elevated altitude to be simulated. Carbon dioxide (CO.sub.2) absorber material is incorporated in the system to remove CO.sub.2 from the air drawn from the reservoir for inspiration by the user.